RationalDMIS 2020 三个中心点找正

在模具、覆盖件的检测中，经常遇到没有特定基准，或则指定的基准位置无法用常规的方法找正，因此，必须有一些特殊的找正方法。 

  功能：三个中心点找正建立坐标系的方法简称三点找正，主要应用在三点确定工件位置的情况。

  说明：三个中心点必须是空间的非矢量元素，能确定准确的位置。元素包括点、圆、椭圆、球、方槽、圆槽，但是点必须采点位置准确，圆、椭圆、方槽、圆槽必须投影才可建立坐标系。

在日常检测中，如果遇到被检测零件指定的基准位置无法用常规的方法找正，则可以观察零件的结构，根据零件的形状和摆放位置，选择三个中心点进行找正。

一般情况下是选择三个球心或三个孔心（圆孔、方孔、椭圆），这种利用三个球心/孔中心就可以实现零件找正的方法即为三个中心点找正。

固定好被检测的零件，选择位于零件上的三个中心点，例如选择了两个圆和一个方槽孔，手动打点。

$$/* Header DMISMN/'Created by [爱科腾瑞科技(北京)有限公司-091521-DEMO-11022(华清)] on 星期五, 六月 18, 2021', 4.0 UNITS/MM, ANGDEC, MMPS WKPLAN/XYPLAN PRCOMP/ON TECOMP/ON FLY/1.0000 MODE/MAN SNSET/APPRCH, 2.0000 SNSET/RETRCT, 2.0000 SNSET/DEPTH, 0.0000 SNSET/SEARCH, 10.0000 SNSET/CLRSRF, 20.0000 RECALL/D(MCS) SNSLCT/S(40-D2) GEOALG/BF, LSTSQR GEOALG/ANGLB, DEFALT GEOALG/CIRCLE, LSTSQR GEOALG/ARC, LSTSQR GEOALG/PLANE, LSTSQR $$ $$ $$*/ MODE/MAN F(CIR1)=FEAT/CIRCLE,INNER,CART,31.5000,31.5000,0.0000,0.0000,0.0000,1.0000, 20.0000 $$ Measurement points are created through nominal points RMEAS/CIRCLE, F(CIR1), 5, VECBLD, 2.0000, 3 PTMEAS/CART, 24.4289, 24.4289, 0.0000, 0.7071, 0.7071, -0.0000 GOTO/CART, 28.3221, 25.2630, 0.0000 GOTO/CART, 30.4050, 24.5862, 0.0000 GOTO/CART, 32.5950, 24.5862, 0.0000 PTMEAS/CART, 36.0399, 22.5899, 0.0000, -0.4540, 0.8910, -0.0000 GOTO/CART, 36.4497, 26.5503, 0.0000 GOTO/CART, 37.7370, 28.3221, 0.0000 GOTO/CART, 38.4138, 30.4050, 0.0000 PTMEAS/CART, 41.3769, 33.0643, 0.0000, -0.9877, -0.1564, -0.0000 GOTO/CART, 37.7370, 34.6779, 0.0000 GOTO/CART, 36.4497, 36.4497, 0.0000 GOTO/CART, 34.6779, 37.7370, 0.0000 PTMEAS/CART, 33.0643, 41.3769, 0.0000, -0.1564, -0.9877, -0.0000 GOTO/CART, 30.4050, 38.4138, 0.0000 GOTO/CART, 28.3221, 37.7370, 0.0000 GOTO/CART, 26.5503, 36.4497, 0.0000 PTMEAS/CART, 22.5899, 36.0399, 0.0000, 0.8910, -0.4540, -0.0000 ENDMES F(CIR2)=FEAT/CIRCLE,INNER,CART,52.4500,11.5500,0.0000,0.0000,0.0000,1.0000, 6.7960 $$ Measurement points are created through nominal points RMEAS/CIRCLE, F(CIR2), 5, VECBLD, 2.0000, 3 PTMEAS/CART, 49.1315, 10.8192, 0.0000, 0.9766, 0.2151, -0.0000 PTMEAS/CART, 52.1195, 8.1681, 0.0000, 0.0973, 0.9953, -0.0000 PTMEAS/CART, 55.5642, 10.1906, 0.0000, -0.9165, 0.4000, -0.0000 PTMEAS/CART, 54.7052, 14.0918, 0.0000, -0.6637, -0.7480, -0.0000 PTMEAS/CART, 50.7295, 14.4803, 0.0000, 0.5063, -0.8623, -0.0000 ENDMES F(SLT1)=FEAT/CPARLN,INNER,ROUND,CART,41.5000,65.1000,0.0000,0.0000,0.0000,1.0000,-0.7071,0.7071,0.0000, 35.0000, 10.0000 $$ Empty VECBLD Block RMEAS/CPARLN, F(SLT1), 6, VECBLD, 3.0000, 3 ENDMES F(CIR1)=FEAT/CIRCLE,INNER,CART,31.5000,31.5000,0.0000,0.0000,0.0000,1.0000, 20.0000 F(CIR2)=FEAT/CIRCLE,INNER,CART,52.4500,11.5500,0.0000,0.0000,0.0000,1.0000, 6.7960 F(SLT1)=FEAT/CPARLN,INNER,ROUND,CART,41.5000,65.1000,0.0000,0.0000,0.0000,1.0000,-0.7071,0.7071,0.0000, 35.0000, 10.0000 DMESW/COMAND,'3PtsCRDBestfitAveErr/OFF' D(CRD1) = LOCATE/FA(CIR1), FA(CIR2), FA(SLT1)